Emission properties of erbium-doped Ge-Ga-Se glasses, thin films and waveguides for laser amplifiers

Abstract

We report, for the first time, Er-doped Ge-Ga-Se films and waveguides deposited using co-thermal evaporation and patterned with plasma etching. The emission properties of the bulk glasses were studied as a function of Erbium doping, showing for the first time that there is a clear concentration quenching effect in the Ge-Ga-Se glasses with a linear radiative lifetime degradation slope of −0.48 ms/mol% Er from a low concentration lifetime of 1.7 ms, even when sufficient Gallium is present to ensure homogeneous distribution of the Erbium. A region between approximately 0.5 and 0.75 mol% Erbium however is shown to provide sufficient doping, good photoluminescence and adequate lifetime to envisage practical planar waveguide amplifier devices. Film emission properties at 0.7 mol% doping were studied and compared with the bulk counterpart showing adequate lifetimes and photoluminescence. Erbium doped films with ~0.8 dB/cm propagation loss at 1550 nm limited by Mie scattering off small particles ejected from the evaporation crucible were fabricated. Planar hybrid Er-Ge-Ga-Se/As2S3 rib waveguides fabricated through photolithography and plasma etching demonstrated propagation losses of ~2 dB/cm at 1650 nm limited by particulate scattering.